Education reporter

Global climate change isn’t just bringing warmer weather to Georgia and the Southeast. It’s also bringing a seemingly contradictory combination of more extreme precipitation events and more drought, University of Georgia climate scientist Marshall Shepherd told a University of Georgia audience on Friday.

Meanwhile, global water scarcity is growing, said Shepherd, the 2013 president of the American Meteorological Society and director of UGA’s Atmospheric Sciences Program.

The global water supply is a fragile one, said Shepherd, a keynote speaker at a UGA symposium and workshop on the science of sustainability in the Georgia Center for Continuing Education.

Only about 2.5 percent of the earth’s water is fresh water, and about two-thirds of that freshwater is in glaciers. About 30 percent is in groundwater, much of it not easily accessible, leaving about 1.2 percent as surface water such as streams or lakes.

As a result, areas that include most of the Southwestern United States and most of Africa, among other places, face challenges in ensuring sustainable water supplies in coming years, he said.

The fastest-growing places are also the ones most vulnerable to water shortages, he said. Georgia’s 2007 drought was “garden variety” by historical standards. But because millions of people now rely on the same water supplies, it felt to some like the worst drought ever.

The earth is getting warmer, especially in recent decades, he said. Much of the warming is occurring in Arctic regions, he said, displaying a map that showed global temperature increases over about a century.

But global warming is just one example of how the Earth’s climate is changing as a result of burning fossil fuels and other human activities.

“When we talk about warming, I don’t like to focus just on warming. I like to focus on how the Earth is responding,” he said.

Another example is extreme weather events, he said.

We’re already seeing evidence around the world of more extreme weather events such as floods, droughts, heat waves and cold spells. The evidence is less clear about snowfall or the frequency and intensity of hurricanes or tornadoes, he said.

He showed maps displaying some of the ongoing climatic changes.

One map from the National Resource Defense Council showed a large increase in the entire southeastern United States and in much of the West of days of extremely low stream flow during the years 2000-2009, compared to averages compiled from weather measurements between 1961 and 1990.

Another U.S. map showed the increase of “extreme” precipitation events, when rain or snow falls in amounts that are in the 99th percentile of intensity. The Southeast saw a 26 percent increase in such events between 1958 and 2011. In the Northeast, the increase was 74 percent, according to data that will be part of the National Climate Assessment, scheduled to be made public this spring.

One solution to coping with global climate change is simply education, as Shepherd noted that average U.S. science literacy is about at an eighth-grade level.